Bearing unit

Abstract

A bearing unit in which two oil sintered slide bearings are fitted in a bearing space of non-magnetic bearing housings to be spaced away from each other and a magnetic fluid is interposed between a rotary shaft and the oil sintered slide bearings to rotatably support the rotary shaft. The rotary shaft is made from a material having permeability, and a ring-shaped permanent magnet is fixedly provided between the two oil sintered slide bearings to be spaced therefrom. The magnetic fluid is held between the two oil sintered slide bearings to be circulated.

What is claimed is: 
     
       1. A bearing unit comprising: non-magnetic bearing housings;   a rotary shaft made from a material having permeability and provided within said non-magnetic bearing housings;   two oil sintered slide bearings fitted in said non-magnetic bearing housings to be spaced away from each other;   a magnetic fluid interposed between said rotary shaft and said oil sintered slide bearings to rotatably support said rotary shaft, and   a ring-shaped permanent magnet fixedly provided between said two oil sintered slide bearings to be spaced therefrom.   
     
     
       2. A bearing unit comprising: non-magnetic bearing housings to form a bearing space which is open at its one end and closed at its other end;   a rotary shaft made from a material having permeability and provided within said bearing space of said non-magnetic bearing housings;   two oil sintered slide bearings fitted in said bearing space of said non-magnetic bearing housings to be spaced away from each other;   a magnetic fluid interposed between said rotary shaft and said oil sintered slide bearings to rotatably support said rotary shaft, and   a ring-shaped permanent magnet fixedly provided between said two oil sintered slide bearings to be spaced therefrom.   
     
     
       3. A bearing unit comprising: non-magnetic bearing housings to form a bearing space having open ends;   a rotary shaft made from a material having permeability and provided within said bearing space of said non-magnetic bearing housing;   two oil sintered slide bearings fitted in said bearing space of said non-magnetic bearing housings to be spaced from each other;   a magnetic fluid interposed between said rotary shaft and said oil sintered slide bearings to rotatably support said rotary shaft, and   a ring-shaped permanent magnet fixedly provided between said two oil sintered slide bearings to be spaced therefrom.   
     
     
       4. A bearing unit as defined in one of claims 1 to 3, further comprising at least one ring-shaped member made from a porous material having a pore greater in diameter than that of said oil sintered slide bearings, said ring-shaped member being disposed outside said oil sintered slide bearings to come closely into contact therewith. 
     
     
       5. A bearing unit as defined in one of claims 1 to 3, wherein said oil sintered slide bearings are press fitted in said bearing housings by means of a sizing pin. 
     
     
       6. A bearing unit as defined in one of claims 1 to 3, wherein said bearing housing comprises two split halves, into which said oil sintered slide bearings are respectively press fitted by means of a sizing pin, and then said two split halves are joined to each other from both ends of said rotary shaft to which said permanent magnet is fixedly secured.